Slovakia E-Invoicing 2027: What Should SAP S/4HANA Users Prepare for Peppol?

From January 1, 2027, Slovakia will require structured E-Invoices for many domestic business transactions. SAP S/4HANA users must assess invoice types, receiving processes, certified delivery providers and tax-data reporting; existing PDF workflows will not suffice.

SAP S/4HANA users in Slovakia must decide how their billing and accounts-payable systems will exchange structured invoices from January 1, 2027. The deadline follows Act No. 385/2025, not a new requirement announced by a software vendor. Slovakia allows voluntary participation in 2026 to test integrations.

A recent Docnova/Melasoft article describes an SAP add-on and standalone cloud portal. These are commercial options, not legally prescribed solutions. Either must meet applicable invoicing, delivery, reporting and recordkeeping requirements.

Under the transitional provisions in Section 85o of Slovakia's VAT Act No. 222/2004, as amended, VAT-registered suppliers generally must issue structured electronic invoices for qualifying domestic supplies to taxable persons and certain non-taxable legal entities. The rule also covers advance payments connected with those supplies. Recipients have a broader obligation to be capable of receiving electronic invoices, including businesses that are not themselves VAT payers.

Not every retail sale requires a Peppol invoice. Ordinary sales to private consumers are outside the domestic B2B invoicing mandate, and the legislation contains exceptions for certain exempt supplies and specified simplified invoices. Existing eKasa and Fiscal Receipt obligations remain separate. A checkout transaction may require different treatment for a consumer and a business buyer.

The existing 15-day invoicing period generally continues for covered supplies and advances. An electronic correction must identify the original invoice and the changed information; where the original invoice was transmitted through the regulated delivery service, the corrective document must follow that route as well. Correcting an issued invoice differs from resending a technically rejected document.

An E-Invoice is structured, machine-readable data meeting European standard EN 16931 and the prescribed syntaxes; sending an ordinary PDF by email does not satisfy that definition. Slovakia is implementing Peppol BIS Billing, based on UBL 2.1, with registered certified delivery-service providers commonly called Digital Postmen. Users can connect through ERP software or a provider-based web portal.

The delivery process is linked to reporting. Under Section 85o, specified invoice information must be communicated to the Financial Administration when qualifying invoices are exchanged through the delivery service. Reporting deadlines generally run to five days from issuance for the supplier and five days from receipt for an in-scope VAT-registered recipient. The statutory obligation is treated as fulfilled when the electronic invoice is handed to the delivery service. Official guidance explains that the provider generates and sends the Slovak Tax Data Document (SK TDD) used for this reporting flow.

The law also addresses transmission by methods other than the regulated delivery service where the recipient consents. Their legal and reporting consequences require separate verification. VAT payers must retain electronic invoices for ten years after the end of the relevant calendar year, so archiving and evidence of transmission belong in the implementation plan.

One route integrates invoice generation and receipt into SAP. In the commercial example published by Melasoft, an add-on maps SAP Sales and Distribution (SD) and Financial Accounting (FI) documents to Peppol-compatible invoice data. It validates outgoing files, displays delivery status and supports processing incoming supplier invoices. The provider's described architecture connects SAP through integration middleware to its Docnova Peppol access point. These interfaces require validation against the SAP deployment.

Another route is a standalone software-as-a-service portal. Users prepare, send, receive and review invoices outside SAP. This may suit low invoice volumes, but manual entry or import could still be needed. Neither an SAP add-on nor a particular SaaS portal is mandatory by law. Businesses should verify the delivery provider's presence in the Financial Administration's official certified-provider register rather than rely solely on a vendor's description.

For retailers and retail chains, the difficult work may be classifying transactions consistently across store sales, e-commerce orders, corporate customers, advance payments and subsequent corrections. Invoice data originating in a Point-of-Sale System (POS), web shop or separate billing application may have to reach SAP with the correct buyer identifiers, VAT treatment and document references. E-Invoicing does not replace eKasa fiscalization or accounting rules.

ERP integrators and E-Invoicing providers must address the other side of the process: incoming invoice validation, posting controls, status tracking and recovery from transmission errors. A rejected electronic file and a legally issued invoice requiring correction are different scenarios. Both scenarios need documented resolution and an Audit Trail.

What should businesses prepare before January 2027?

Affected businesses should inventory Slovak invoice and credit-note types, identify which transactions fall within the mandate, and review customer and supplier master data. They should confirm that their software can produce and read compliant structured documents, select and authorize a certified Digital Postman, and test both outbound delivery and inbound processing. Tests should cover advances, invoice corrections, rejections, reporting statuses and long-term electronic archiving.

From a retail compliance perspective, selecting the technology is only one part of the project. The greater risk is treating all checkout documents as B2B E-Invoices, or assuming that successful transmission proves the VAT treatment and accounting data are correct. Companies should test real scenarios with ERP, POS and provider teams during 2026.

The principal legal basis is Act No. 385/2025: Tlač predpisu, Slovakia's VAT Act No. 222/2004: 222_2004from01012025.pdf, official information is available through the Slovak Financial Administration's E-Invoicing portal, its implementation guidance 1/DPH/2026/I, and its September 10, 2026 clarification: News detail - PFS.

Mirko Bijeljanin, Junior Legal Consultant at Fiscal Solutions

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